"It's a long season. It's a lot like climbing a mountain, it's a lot like running a marathon. You have some really great moments of achievement and you have some disappointing things that happen," Brady said. "It's tough and it's a struggle and it's a daily grind in discipline, determination, mental toughness, all those things that are really intangible to an individual, maybe things you can't necessarily measure, but in the end, that's what probably matters more than anything you can measure."

The star quarterback reflected on the culture among Patriots players.

"Guys, how they bring a positive, competitive, winning attitude every day has been a great culture for me to be around," Brady said. "The reason why we've been to nine Super Bowls was because guys, they want to bring their best and compete every day for the teammate next to them and you never want to let your teammates down."